Right coil for this job? I'm not comfortable with contractor response...

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Right coil for this job? I'm not comfortable with contractor response...

Hello. This is my first post here but I've searched these forums extensively before making my purchasing decisions on my new AC/Furnace units. I found the responses very helpful and intelligently written so I'm hoping someone can help me with the one thing I really didn't research beforehand - the coil unit. I'm concerned the contractor did not install the right coil since there is not a system (ac & furnace) match in the AHRI database for this equipment I bought. And I think this coil disqualifies me from the tax credits ($300) I was expecting on the AC unit.

These are the items I just had installed :

Lennox
Furnace : SL280UH090V36B
AC : XC17-036-230

ADP Coil
L*19/36S9+TD

The AHRI ref number is 3895347. When I look this up, it lists the Lennox AC unit but not the furnace - and says this coil doesn't qualify my system for the tax credits.

When I look up AHRI ref number 3952589 it is the right match for my system and looks to be almost the same coil without the +TD on it. However the efficiency is higher and thus qualifies for the tax credits. I'm guessing this takes the furnace blower into account?

So I contacted the installation manager of the installation company. This was his response :

The coils that we used is an adp brand which is a make of lennox products. Their ahri ratings are not really true numbers and actually all their coils no matter what model have the exact same performance ratings.

The only difference between the 2 coils is the TD at the end and all that is, is a time delay which helps in achieving the efficiencies that the cols are rated at.

In short you meet all the requirements for efficiency.

Yet clearly I see two different AHRI numbers for Capacity/EER/SEER numbers when I compare them. Should I be concerned? Is this considered an undersized coil and I am not getting the best performance from my AC unit?

I don;t think that's an undersized coil. I don't know Lennox number that well, but I suspect it's a 19" wide, 3 ton coil. A 90k Lennox furnace probably has a 19" wide case. Oddly, it appears to only have a 3 ton blower, which I think is unusual for a 90k furnace.

If the models numbers match what's shown on the AHRI certificate and it meets the minimum effceincy requirements, you fine. Don;t worry about it.

In reality, he's partly right. They use computer simulations for a lot of the coils, not real tests. In hte real world, actual delivered performance can vary widely based on lineset length, refrigerant charging, condenser location, and especially ductwork design and the resulting static pressure. A 3 ton AC needs abotu 1200CFM. I could show you an installtion where the furance blower uses 450Watts to reach 1200CFM and another were it only needs about 300 Watts. That is equal to going from a 16 SEER system to a 15 SEER system. A shift from 0.2" static pressure to 0.9" static pressure. Going from 0.5" to 0.9" would be about a 1/2 SEER.

I'm just wondering why they would use an ADP coil on a signature series unit. You paid money for the best. Although it may technically be the same thing, you should have got an actual Lennox CH33 series coil. That's my opinion anyway.

I'm just wondering why they would use an ADP coil on a signature series unit. You paid money for the best. Although it may technically be the same thing, you should have got an actual Lennox CH33 series coil. That's my opinion anyway.

I agree with Brian on this! Why use a adp coil with a Lennox system? The only thing that comes to mind is eff. Numbers being better with the Adp coil. I would just ask installing company about Lennox coil that matchs up with the system compaired to adp coil.

What does your original paperwork/ estimate show as far as the coil, furnace and a/c unit? If the same as what was installed and meets eff. Numbers for tax credit and the warranty is the same then nothing to worry about.

That's part of my concern about this coil - the AHRI certificate (ref 3895347) doesn't state that it is eligable for the tax credit. It lists the EER as 12.5 and the SEER as 15. I see many other coils that are 13+ EER and 16+ SEER that I think would have worked for this system. The certificate only lists the AC unit and doesn't list with furnace, which was replaced at the same time...

I just looked through the original quote and there is no mention of which coil they were going to use.